2. Structure of the Heart - covered by the pericardium which is a sac surrounding the heart - it is made up of 3 layers - produces serous fluid to decrease friction
3. Wall of the Heart 3 Layers 1. Epicardium - provides protection - deep part contains fat along blood vessels 2. Myocardium - thickest layer – mostly cardiac muscle tissue - forces blood out of the heart chambers - contains many capillaries & nerve endings
4. 3. Endocardium - contains Perkinje fibers – specialized nerve fibers used during the heart beat
7. Blood supply to the heart a) coronary artery - supplies blood to heart muscles b) cardiac veins - takes blood away from heart muscles – empties into the coronary sinus The cardiac cycle movie
8. Actions of the Heart Cardiac Cycle - consists of the atrias contracting (atrial systole) followed by the contracting of the ventricles (ventricular systole) followed by a brief relaxation of the heart (diastole) Heart Sounds - lubb - ventricles contracting - tricuspid and bicuspid valves closing - dupp - ventricular relaxation - pulmonary & aortic valves closing
9. Cardiac Conduction System - specialized cells initiate and conduct impulses through the myocardium SA node AV node AV bundle Perkinje fibers
10. 1. Sinoatrial node (SA node) - start impulses with no connection to nervous system - stimulates atrias to contract - a.k.a. the pacemaker 2. Atrioventricular node (AV node) - causes a delay in signal - impulse passes into AV bundle - causes impulse speed to increase - separates into perkinje fibers - ventricles contract - force blood out of ventricles
11. Electrocardiogram (ECG or EKG) recording of electrical changes during cardiac cycle Cardiac conduction movie
12. P wave – impulse spreading from SA node to AV node - atria depolarize QRS Complex – spreading of impulse from AV node to ventricles - ventricles depolarize T wave – ventricles repolarize
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14. Regulation of the Cardiac Cycle - depends on: physical exercise body temp concentration of various ions - when heart rate needs to be changed, the cardiovascular center in the medulla oblongata sends impulses to the SA node - secretes ACH ( heart rate) - secretes norepinephrine ( heart rate
15. Blood Vessels Structure a. tunica externa tunica externa - outer most layer - contains elastin and collagen fibers
16. b. tunica media tunica media - middle layer - contains the muscles to allow for vasoconstriction and vasodilation
17. c. tunica interna tunica interna - inner layer - primarily simple squamous epithelium the endothelium - prevents blood clotting by providing a smooth surface
18. 1. Arteries - have thick muscular walls - carry blood away from the heart 2. Arterioles - little arteries - help to regulate blood flow to capillaries
19. 3. Capillaries - wall is made up of endothelium 1 cell thick - found near every living cell - high metabolic tissues have a greater density of capillaries - functions in gas exchange and filtration
20. 4. Venules - small veins - drain blood from capillaries 5. Veins - carry blood toward the heart - have thinner walls than arteries (less muscle) - act as a blood reservoir - contains valves to prevent the backflow of blood
21. Blood Pressure the hydrostatic pressure exerted by blood on the walls of blood vessels - there is a high bp in the arteries and low bp in the veins - must have a pressure difference in order for blood to flow
22. Factors Affecting Blood Pressure 1. Blood volume - volume = bp - volume = bp 2. Blood vessel radius - radius = bp - radius = bp - the radius can be affected by physical activity, overall health, stress, hormones
23. 3. Blood viscosity - the “thickness” of the blood - due to decrease water or anemia viscosity = bp 4. Total blood vessel length - length = bp 5. Heart action - heart forces blood into arteries - force = bp
24. - stroke volume – amt. of blood discharged from ventricles - ~ 70 mL - cardiac output – amt. of blood discharged from ventricles per minute - ~5,040 mL Measuring Blood Pressure - measured with a sphygmomanometer - systolic pressure – maximum pressure - diastolic pressure – minimum pressure
25. Clinical Applications asystole – failure of the myocardium to contract sinus rhythm – the normal cardiac rhythm regulated by the SA node myocardial infarction – death of the heart muscle tissue (heart attack)
26. heart murmur – a valve does not close properly causing some blood to leak “backward” to the previous chamber hypertension – high blood pressure
27. spider veins – a milder form of varicose veins varicose veins – enlarged, dilated veins that are seen through the skin
28. aneurysm – a sac that forms in a blood vessel due to a weakened artery atherosclerosis – deposit of fatty materials (plaque) on the walls of blood vessels
